Processing, Structural Analysis, and Enzymatic Degradation of Poly(ethylene succinate) Melt-Spun Fibers

Biodegradable fibers with sufficient tensile strength for general-purpose applications were successfully fabricated from biobased poly(ethylene succinate) (PES) via a three-step process comprising intermediate annealing, heat drawing, and final annealing. Crystallization behaviors were first evaluated using isothermal half-crystallization times, which showed rapid crystallization at 50–60 °C (∼1 min) and significantly slower crystallization at 5 °C (∼150 min). Based on this result, amorphous fibers were produced into ice–water quenching and drawn without prior crystallization, yielding a tensile strength of 183 MPa and a Herman’s orientation function ( f ) of 0.42. In contrast, fibers subjected to intermediate annealing prior to drawing showed improved properties (462 MPa, f = 0.83), suggesting that prior crystallization enhances orientation stability during drawing. However, crystallization-induced stiffening limited drawability, which was overcome by introducing heat drawing. This enabled an 11-fold draw at 60 °C, resulting in fibers with a tensile strength of 501 MPa and f = 0.93. Enzymatic degradation tests revealed that as-spun fibers degraded more rapidly than crystal-oriented fibers. These findings suggest that molecular orientation plays a key role in both mechanical and degradation behavior. PES fibers offer a promising sustainable alternative to petroleum-based plastic fibers for applications such as fishing nets, agricultural materials, and other outdoor-use textiles.